Comments on: SQL SERVER – Four Posts on Removing the Bookmark Lookup – Key Lookup http://blog.sqlauthority.com/2010/05/13/sql-server-four-posts-on-removing-the-bookmark-lookup-key-lookup/ Personal Notes of Pinal Dave Fri, 17 May 2013 15:26:57 +0000 hourly 1 http://wordpress.com/ By: SQLAuthority News – Monthly Roundup of Best SQL Posts Journey to SQL Authority with Pinal Dave http://blog.sqlauthority.com/2010/05/13/sql-server-four-posts-on-removing-the-bookmark-lookup-key-lookup/#comment-73942 Mon, 31 May 2010 01:32:30 +0000 http://blog.sqlauthority.com/?p=8954#comment-73942 [...] SQL SERVER – Size of Index Table for Each Index – Solution 2 SQL SERVER – Size of Index Table for Each Index – Solution 3 – Powershell SQL SERVER – Four Posts on Removing the Bookmark Lookup – Key Lookup [...]

]]> By: BBeadle http://blog.sqlauthority.com/2010/05/13/sql-server-four-posts-on-removing-the-bookmark-lookup-key-lookup/#comment-70860 Fri, 14 May 2010 15:39:44 +0000 http://blog.sqlauthority.com/?p=8954#comment-70860 I’ve been looking at a query that one of our third-party applications uses to populate one of its forms. I’ve found that it does a “SELECT *” from a table, with a sub query against the same table. The estimated execution plan shows a Key Lookup at a cost of 99%.

I considered adding an index that included all of the columns in the table– not sure if that was even a good idea but I was going to try it as a test. However, the table contains a number of ntext fields that cannot be included in the index. Kick blocked.

Given that I cannot modify either the query itself as it is hard-coded, or the underlying table structures for the same reason– is there anything I can do to improve the performance of the query?

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